Apparatus for improving steering sensitivity of vehicle

Abstract

A vehicle steering feel improving apparatus is provided for a vehicle, wherein the vehicle is capable of running with a road wheel driven by a driving force from a power source. The vehicle steering feel improving apparatus includes a steering operation detecting means that detects a condition that steering operation is being performed to steer a steerable wheel of the vehicle. A driving force fluctuating means repeatedly fluctuates the driving force to the road wheel, while the steering operation detecting means is detecting the condition that steering operation is being performed.

The invention claimed is: 
     
       1. A vehicle steering feel improving apparatus for a vehicle, wherein the vehicle is capable of running with a road wheel driven by a driving force from a power source, the vehicle steering feel improving apparatus comprising:
 a steering operation detecting means that detects a condition that steering operation is being performed to steer a steerable wheel of the vehicle; and 
 a driving force fluctuating means that repeatedly fluctuates the driving force to the road wheel, while the steering operation detecting means is detecting the condition that steering operation is being performed. 
 
     
     
       2. The vehicle steering feel improving apparatus as claimed in  claim 1 , wherein the steering operation detecting means detects that steering operation is performed, based on a difference in rotational speed among a plurality of road wheels of the vehicle. 
     
     
       3. The vehicle steering feel improving apparatus as claimed in  claim 1 , wherein the driving force fluctuating means performs at least a driving force increasing operation of increasing the driving force to the road wheel for repeatedly fluctuating the driving force to the road wheel. 
     
     
       4. The vehicle steering feel improving apparatus as claimed in  claim 3 , wherein the driving force fluctuating means performs the driving force increasing operation first when repeatedly fluctuating the driving force to the road wheel. 
     
     
       5. The vehicle steering feel improving apparatus as claimed in  claim 1 , wherein the driving force fluctuating means allocates a longer time period to the driving force increasing operation than to a driving force reducing operation, while repeatedly fluctuating the driving force to the road wheel. 
     
     
       6. The vehicle steering feel improving apparatus as claimed in  claim 5 , wherein the driving force fluctuating means sets the time period of the driving force increasing operation and the time period of the driving force reducing operation to constant ratios, regardless of steering speed. 
     
     
       7. The vehicle steering feel improving apparatus as claimed in  claim 1 , wherein amount of fluctuation of the driving force is such that a passenger of the vehicle does not feel acceleration nor deceleration. 
     
     
       8. The vehicle steering feel improving apparatus as claimed in  claim 1 , wherein the driving force fluctuating means sets the driving force to the road wheel to a larger value and to a smaller value than a target driving force as a reference, while repeatedly fluctuating the driving force to the road wheel, wherein the target driving force is determined based on a state of operation of the vehicle. 
     
     
       9. The vehicle steering feel improving apparatus as claimed in  claim 1 , wherein:
 the vehicle is an electric vehicle in which at least part of the driving force is supplied by an electric motor; and 
 the driving force fluctuating means performs through the electric motor a control of repeatedly fluctuating the driving force to the road wheel.